Adobe Webfonts on multiple sites from one CC account

I am trying to get to the bottom of what will happen come the 31st of December with regards to websites using Adobe Fonts, I understand that client sites will now require there own license/CC subscription to continue using fonts on their sites. However I want to understand what will actually happen on the 1st of January, will the fonts on their site stop working and default to the next in the stack? I need to clarify this with clients so they can calculate thier costs and options, will it only be a CC subscription that will work or will you be offering any options to just subscribe to Adobe Fonts.

I also planned to use fonts on multiple internal sites,  each on their own domain, and I am interested how this will work, and how the distinction will be able to be made between what is one of my "other" sites and a clients site?

Any help on this matter would be appreciated!

Thanks

And